Banks are demanding that the Consumer Financial Protection Bureau relinquish the right to sue over certain flawed mortgage originations, in exchange for their participation in a proposed multibillion-dollar settlement of alleged foreclosure abuses.

The banks say their inability to secure a sufficiently broad release from the new bureau, which was sidelined in earlier discussions as it launched, would be a deal breaker. The five biggest U.S. mortgage banks, state attorneys general and Obama administration officials are pushing to finalize a deal before the end of the year that would be worth $19 billion or more.